Cross wind drag and side skirts / 'tails

[Cd]

A few years ago, I added side skirts to my Civic.
I removed them since they add several feet of frontal area to the car when hit by a crosswind. *

What kind of FE hit does a car get from increased side frontal area ?

On a similar thought, what about boattails and the increase in frontal area that they produce ?

* Where I live ( the 'hill country' ) , there is a lot of wind that blows in from the sides of the car.

[Cd]

I wonder how crosswinds affect semis regarding FE.
I know that the semi becomes less stable, but is there also a big FE hit ?

[aerohead]

Originally Posted by Cd

A few years ago, I added side skirts to my Civic.
I removed them since they add several feet of frontal area to the car when hit by a crosswind. *

What kind of FE hit does a car get from increased side frontal area ?

On a similar thought, what about boattails and the increase in frontal area that they produce ?

* Where I live ( the 'hill country' ) , there is a lot of wind that blows in from the sides of the car.

Skirts should not project below the "bottom" of the vehicle and consequently should not aggravate it's side area.
I can't answer the question about drag vs increased side area.I've never seen anything published on it.There is a table published by EPA on wind/mpg effects.
One benefit of skirts in crosswind,is that they help cancel roll moments above the C.G.,actually increasing stability and safety to an 18-wheeler.
I've only run "short" tails,so I can only address those,and my experience so far is that they offer no degradation of stability,thanks to Professor Morelli's work at Pininfarina.

[tasdrouille]

I can only imagine underside airflow at a yaw angle is extremely complex. I don't think side skirts have a negative impact on drag even in crosswinds. Remember, the flow vector is very rarely gonna be perpendicular.

[BamZipPow]

Originally Posted by Cd

A few years ago, I added side skirts to my Civic.
I removed them since they add several feet of frontal area to the car when hit by a crosswind. *

Got any piccies of yer vehicle with the side skirts on?

[Cd]

Originally Posted by BamZipPow

Got any piccies of yer vehicle with the side skirts on?

I knew that was coming ...............I'll have to find them.

( Not sure if I deleted them. )


EDIT : I found this picture, but it has some quick and sloppy Photoshop work . The skirts and wheel gap filler are real, but the diffuser thingee etc are Photoshop additions.



Phil : When you say that the skirts shouldn't project below the 'bottom' of your vehicle, what do you mean ? Do you mean the floorboard ??
( surely not )


Tas : Can you simplify what you said about 'flow vectors' going perpendicular ?
( Imagine that you are trying to explain what you just said to someone with the mental capacity of a child ...... or a very smart monkey . )

[Bicycle Bob]

Well, if you get a crosswind on a sailboat, and increase the sail area, it goes faster. Most of the rigid-wing sailing cars have not had a way to adjust for right or left crosswinds. I saw Mana La get hit by a gust, and the acceleration was obvious. Second Inning: Mana La Solar Car Put On Display At Peterson Automotive Museum - Green Diary YMMV

[BamZipPow]

I'll show you mine...

[puddleglum]

http://http://www.bentleypublishers....ery-768-8.html

Frank Lee posted this link in response to a question I had on crosswind.

http://http://207.242.75.40/derbtech/windeff.htm

Here is another one that I found. Both have good explanations of crosswind vectors.

[BamZipPow]

Originally Posted by puddleglum

Race Car Aerodynamics - Designing for Speed *-* Bentley Publishers - Repair Manuals and Automotive Books

Frank Lee posted this link in response to a question I had on crosswind.

Wind Effects

Here is another one that I found. Both have good explanations of crosswind vectors.

Fixed yer links...